"John Hines" wrote in message
...
"Sean R. Kerns" wrote:

The other thing I noticed a little while ago was that the "oil" seems to
disappear at night, which makes me wonder if it's even oil at all. Is it
possible it's just some kind of algae haze?

It is entirely possible, and natural to get a tiny bit of oil, if your
pond is frequented by wildlife. It is just natural body (feather, fur)
oil that gets washed off.

As suggested, some means to overflow your pond, so that the floating oil
drains away.

I get this fairly frequently in my natural pond - especially after prolonged
periods without rain and I have no pumps etc. and I don't feed the fish .
The birds idea sounds fairly good, I noticed some oil on the surface of my
pond today and co-incidentally there was a lot of evidence of birds bathing.